libxslt - security update

Several vulnerabilities were discovered in libxslt, an XSLT processing
runtime library, which could lead to information disclosure or
denial-of-service (application crash) against an application using the
libxslt library.

For the stable distribution (jessie), these problems have been fixed in
version 1.1.28-2+deb8u1.

We recommend that you upgrade your libxslt packages.